Question on Blender add-on code uniqueness

Coding Python Support
1

I built some parts of a Blender add-on by reading forum posts.​

examples:

eyedropper
https ://blenderartists.org/t/how-to-draw-an-object-selection-eyedropper-in-an-addon/1287437/7

parent mesh to bone
https ://blender.stackexchange.com/a/214699

fully deleting object
https ://blenderartists.org/t/detecting-that-a-specific-object-has-been-removed-from-the-scene/1212775/2

set active bone group
https ://blender.stackexchange.com/questions/6870/how-can-the-active-bone-group-be-set-from-a-script/6873#6873

often, the code in the forum post is the most direct way to do something,
or the only way I know how to do something.
below is some code in my add-on:

for example, parent mesh to bone
mat = Matrix.Translation(-pb.vector) #offset by inverse of bone vector
obj.matrix_parent_inverse = pb.matrix.inverted() @ mat

for example, fully deleting object
if arma is not None:
if arma.name not in scene.objects:
bpy.data.objects.remove(scene.properties_tool.arma)
scene.properties_tool.arma = None

Is it a concern that the code in my add-on is too similar?
what to do?

I have not released any add-on(s)
I hope to sell my addon(s)

2

Blender Addons are GPL so you can use it as you like… if you publish them then under GPL…

3

So… I think what you’re asking generally here is whether you’re doing copyright infringement. You can read all you want about it if you query your favorite seach engine with these keywords. Maybe see Which license for small scripts ? also.

I don’t know about blenderartists’s stance on copyright in the author posts, but you can check the one on stackexchange by clicking on the timeline button.

https://blender.stackexchange.com/posts/6873/timeline this one is CC BY-SA 3.0

Although it would be pretty hard for the authors of these lines of code to go to courts against you for basically using public knowledge code readily available in the official API docs and a million other places on the internet.

If you want to credit the authors, there are official guidelines available online for how to do so.

Do bear in mind that you can sell access to your addon, but you won’t be able to stop anyone from redistributing it for free (if they also comply with the license by acknowledging your copyright) if you want to comply with the GPL license.

4

As someone who posts a lot of code on this forum I personally wouldn’t care if someone copy/pasted it into an addon, that’s the whole point of open source after all.

I would raise some concerns on the ethics of selling a product you have no means of supporting, however. What are you going to do when one of your customers finds a bug, post on the forum and hope for the best? Anyone who has sold a commercial addon could tell you that writing the addon is generally the easy part, supporting it takes a lot of time and effort.

2 Likes
5

Or… just look into the origial source :

Blender’s Python API is an integral part of the software, used to define the user interface or develop tools for example. The GNU GPL license therefore requires that such scripts (if published) are being shared under a GPL compatible license. You are free to sell such scripts, but the sales then is restricted to the download service itself. Your customers will receive the script under the same license (GPL), with the same free conditions as everyone has for Blender.

Of course it would be nice to talk with the original authors about this and also mentioning them… and they still give support for them…